Even though people were prepared to admit their guilt to criminal charges, the head of the Criminal Justice Inspectorate (CJI) said plea hearings in front of judges could be held up with significant implications for the public purse.

Brendan McGuigan, the chief inspector who has called on the Department of Justice to deliver and oversee the development of an early guilty plea scheme, has also requested reform of the criminal legal aid fee structure. His recommendations are contained in a new inspection report carried out by his office.

In a statement Mr McGuigan stopped short of pointing the finger at anybody but said: "CJI heard concerns and evidence that incentives may exist to delay plea hearings which attract a higher fee or to escalate matters to a contest or to the crown court, where enhanced fees would be payable."

The chief inspector has called for the creation of a single legal aid fee structure in the magistrates', crown and youth courts. He said the changes could save time, money and spare victims the ordeal of giving evidence.

Mr McGuigan added: "These changes coupled with the principle of the removal of incentives to prolong cases being dealt with in the crown courts would be beneficial in delivering a reduction in the additional costs incurred by the public purse when an offender chooses to change their plea to guilty later in the criminal process."

CJI inspectors interviewed representatives from stakeholders including PSNI, Probation Service, Legal Services Commission and the Department of Justice and the Belfast Solicitors' Association. The Bar Library, which represents defence barristers and the Law Society for solicitors did not respond to invitations to participate.

Inspectors calculated that the differential between guilty plea and contest fees for solicitors in Northern Ireland during 2010/11 ranged between £130 and £390. Inspectors said that although defendants have the right to plead as they wish, annual savings of about £4.07 million could be made if individuals who fully admit their guilt at the earliest opportunity were fast-tracked.

Mr McGuigan added: "Unfortunately this is not always the case and entering an early guilty plea and getting a case to court for hearing and disposal has become a complex and protracted process."

Paul O'Connor, communications officer for the Law Society of Northern Ireland, said: "The CJI report will be considered carefully by the Law Society of Northern Ireland and we will respond when necessary."